Our objective is to conduct a detailed ultrastructural study of the nerve fibers in the organ of Corti and vestibular sense organs. The morphological features of the different fibers will be described and their terminals will be followed by serial sections. The number of nerve endings below the sensory cell will be determined and their fiber population will be counted at Corti's tunnel, habenula perforata and internal auditory canal. A further study will be conducted to determine changes in the nerve endings and fibers after nerve section, acoustic trauma, and kanamycin and streptomycin toxicity. Such information will be valuable in the development of an artificial device to improve the hearing in deaf individuals. Our second major objective is to advance our knowledge on endolymphatic hydrops. The etiology, hearing loss, and pathology of hydrops will be studied further. We will attempt to find a method to prevent the occurrence of experimentally induced hydrops in animals by creating fistulae in the saccule, reopening the blocked site, and the use of drugs and chemicals. Inner ear function will be determined by a behavioral conditioning technique. This study will provide information useful in the treatment of Meniere's disease.